Figure 1. Overview of effects of probiotic lactobacilli on mucosal and systemic immune systems. This figure summarizes the evidences collected from published articles showing the immune compartments affected by probiotic lactobacilli at mucosal and systemic level. In the intestinal fluid, probiotics influence the production of AMPs by Paneth cells, the production of mucus by goblets cells as well as the level of secretory IgA that is under the dependence of APRIL produced by IEC. Probiotics affects the expression level of TLRs on DC as wells as immune cells in Peyer's patches, leading to a production of a wide range of cytokine regulating the evolvement of immune response. Through lymph nodes, immune cells can migrate from lamina propria to circulation, therefore influencing the systemic immune system. This can be noticed by the influence on IgA, IgG levels in serum and the range of cytokines produced by PBMC. The immune cells in spleen are also influenced by probiotics, that is remarked by the variation in cytokines production and stimulation of specific population of lymphocytes. The diverse patterns observed when using probiotics as immunomodulators can be explained by the composition of TA and LTA that varies from strain to strain. , Increase; , Decrease; AMPs, Antimicrobial peptides; APRIL, A proliferation-inducing ligand; B, Lymphocyte B; DC, Dendritic cells; IEC, Intestinal epithelial cells; IgA, IgG, Immunoglobulin A, G; IgA+, IgA-producing cells; IL-1,2, etc., Interleukins 1, 2, etc.; LTA, Lipoteichoic acid; M, Macrophages; Mo, Monocytes; N, Neutrophils; NK, Natural killer; PBMC, Peripheral blood mononuclear cells; RBC, Red blood cells; S-IgA, Secretory IgA; T, Lymphocyte T; TA, Teichoic acid; TGF-β, Transforming growth factor beta; Th1, Lymphocyte T helper producing cytokines inducing cell-mediated immune response; Th2, Lymphocyte T helper producing cytokines inducing humoral-mediated immune response; TLC and DLC, Total and differential leucocyte count; TLRs, Toll like receptors; TNFα, Tumour necrosing factor alpha; Treg, Lymphocyte T helper producing regulatory cytokines.
Download figure to PowerPoint